A liquid crystal display (LCD) device is an appliance capable of controlling transmission/blocking of light (on/off of display) by controlling alignment of liquid crystal molecules having birefringence. There are, as a liquid crystal alignment mode of LCD, a twisted nematic (TN) mode in which liquid crystal molecules having positive anisotropy of dielectric constant are aligned while being twisted at 90° in observation of the liquid crystal molecules from the normal direction of a substrate; a vertical alignment (VA) mode in which liquid crystal molecules having negative anisotropy of dielectric constant are aligned vertically to a substrate face; and an in-plane switching (IPS) or fringe field switching (FFS) mode in which liquid crystal molecules having positive or negative anisotropy of dielectric constant are aligned horizontally to a substrate face and a transverse electric field is applied; etc.
In the vertical alignment mode, the initial alignment of liquid crystal molecules is orthogonal to a substrate face. A method for forming a vertical alignment film on a substrate face of a liquid crystal display device is the mainstream as a method for aligning liquid crystal molecules vertically to a substrate face.
Further, in recent years, a technique for forming a polymer layer (PSA layer) capable of controlling alignment of liquid crystal molecules on an alignment film or on a substrate having no alignment film has drawn attention. A PSA layer is formed by sealing a liquid crystal composition obtained by mixing a polymerizable component such as a monomer, an oligomer, or the like (hereinafter, referred to as monomer or the like for short) with a liquid crystal material between substrates and polymerizing the monomer or the like by heat or light (e.g. ultraviolet) irradiation. The alignment of liquid crystal molecules can be held by such a polymer layer.
Patent Document 1 discloses a liquid crystal display device having no alignment film but a hardened resin layer formed by light irradiation after liquid crystal injection instead. This resin layer is formed by injecting a liquid crystal into an intermediate product of a liquid crystal display panel and thereafter hardening a curable resin containing a monofunctional monomer and a polyfunctional monomer in combination and the functional groups capable of exhibiting vertical alignment of molecules composing the curable resin are generated while being tilted at almost a constant angle to the surface of a substrate to vertically align liquid crystal molecules.